The present invention relates to electrical interconnection structures, and more particularly to interconnect trace and bond pad structures for use in conjunction with slider assemblies carrying transducing heads.
Hard disc drives (HDDs) typically comprise one or more discs, each disc having concentric data tracks for storing data. Where multiple discs are used, a stack is formed of co-axial discs having generally the same diameter. A transducing head carried by a slider is used to read from and write to a data track on a disc. The slider is carried by a head arm assembly (HAA) that includes an actuator arm and a suspension assembly, which can include a separate gimbal structure or can integrally form a gimbal. As the disc is spun, the slider glides above the surface of the disc on a small cushion of air. The actuator arm movably positions the slider with respect to the disc. Electrical connections extend along the suspension to electrically connect the transducing head to components located at or near the actuator arm. Those electrical connections can be formed on the suspension itself, or can be located on a separate interconnect structure supported relative to the suspension, such as a flex-on suspension (FOS).
The slider includes a slider body (called the “substrate”) and an overcoat that includes the transducing head. The slider body is electrically conductive, while the overcoat is electrically insulative. A plurality of bond pads, usually a minimum of four, are formed at a side or edge of the slider—typically at its trailing edge. These bond pads are directly connected through the overcoat to various components, such as to the transducing head or to a heater. During fabrication of a HDD, the bond pads are electrically connected to the electrical connections (i.e., traces) along the suspension. Typically, a conventional gold ball soldering operation is used to make the electrical connections from the bond pads of the slider to the electrical connections of the suspension. Separately, the slider is mechanically secured to a load button or load point of the gimbal at a back side of the slider (synonymously called the “top” of the slider), for example, with an adhesive.
As areal recording density for HDDs increases, the sizes of sliders and transducing heads continue to decrease. Numerous other factors have also influenced smaller slider sizes. Accordingly, sliders can have dimensions of about 1 mm in width, 1.3 mm in length and 200-300 μm in thickness. Trends are for sliders to continue to be smaller, with lengths of 1 mm or less and widths of 700-800 μm or less. The sizes of bond pads decrease accordingly with smaller slider sizes.
Decreasing slider and bond pad sizes present numerous difficulties. For example, conventional methods and equipment used for gold ball bonding are no longer reliable for smaller sliders with small conventional bond pads at a side or edge of the slider. Moreover, less space is available along the sides or edges of the slider for large numbers of electrically isolated bond pads.
Thus, the present invention provides a slider assembly having an alternative slider interconnect trace and bond pad assembly.